1. Field of the Invention
The present invention generally relates to communication systems. More particularly, the invention generally relates to an improved synchronization search technique and more particularly to using a random access sequence generator during the synchronization search process.
2. Background Information
In some cellular networks, information (e.g., voice signals) are encoded with a scrambling code, transmitted to a receiving device, and decoded by the receiving device. In CDMA cellular networks like W-CDMA and CDMA2000 systems, each cell or base station sector uses a different time offset of the scrambling code. To establish a communication link, the mobile station searches for a cell and determines the frame synchronization associated with that cell.
To achieve this synchronization, the mobile station uses a “searcher” to perform initial cell acquisition, cell measurement and delay profile estimation. The mobile station may acquire the scrambling code, code offset, and carrier frequency of the strongest base station when it has no radio link established to any particular base station. The mobile station then may measure the radio link quality of the neighboring cells to support various types of handover procedures. The mobile station then may estimate the delay profile to decide on allocation of Rake fingers or demodulator elements. In general, the searcher tests the hypothesis that a spread spectrum signal exists at a particular code offset and/or at a certain carrier frequency and/or with a certain scrambling code, and so on.
All of these requirements benefit from a high “search throughput” from the mobile station. The “search time” may also greatly impact performance during power up of the mobile device. A method for reducing the search time and increasing the search throughput is desirable.